This invention relates to a multi-lumen catheter for the simultaneous infusion and/or withdrawal of fluids from a patient's body.
Catheters having multiple interior lumens are desirable because they reduce the number of tubes which are passed through a patient's skin and ultimately reduce the risk of infection. Such catheters are commonly employed in hemodialysis treatment. When used in this capacity, these catheters are called dual lumen catheters because they typically comprise two lumens: one to withdraw blood from a patient and the other to deliver the treated blood back to the patient.
Other applications for multi-lumen catheters include simultaneous delivery of incompatible drugs to patients. For example, certain cancer treating drugs cannot be delivered through a common catheter lumen due to their incompatibility, although these drugs may be simultaneously delivered into a patient's body. The ability to simultaneously deliver drugs to a patient promotes the efficient discharge of hospital duties. This aspect is especially important in light of the nursing shortage currently plaguing the health care industry.
Several dual lumen catheters exist for hemodialysis treatment. These catheters have an infusion port, a withdrawal port, and a catheter tip all at a distal or leading end of the catheter. The infusion and withdrawal ports permit fluid communication between a patient's body and their respective lumens. A common feature among these catheters is the location of the infusion port at the most distal point on the catheter tip. An example of this configuration is disclosed in U.S. Pat. No. 4,682,978. The purpose of this catheter tip design is to allow insertion and positioning of the catheter within a blood vessel by advancing the catheter over a guide wire. A problem with prior art catheters is that the discontinuous surface of the catheter tip often results in thrombosis in the frontal area. The indenture in the catheter tip due to the infusion port causes slowing of blood flow at the tip, otherwise known as stasis. Although the leading ends of these catheters are, in several instances, tapered to facilitate insertion, the problems associated with the discontinuity of the catheter tip surface are not surmounted.
A second common feature among dual lumen catheters is the location of the withdrawal port in relation to the infusion port. The withdrawal port is generally located upstream from and proximal to the infusion port. The purpose of this configuration is to assure the withdrawal of only untreated blood. One strategy for the separation of the infusion and withdrawal ports involves the blockage of the withdrawal lumen at a distal end while the infusion lumen continues on through the catheter tip as described in U.S. Pat. Nos. 4,098,275; 4,134,402; 4,385,631; 4,403,983; 4,451,252; 4,493,696; 4,453,087; 4,583,968; 4,619,643; and 4,682,978. Another method of achieving this separation is by providing coaxial infusion and withdrawal lumens wherein the core infusion lumen has a longer length than the annular withdrawal lumen as described in U.S. Pat. Nos. 4,096,860; 4,099,528; and 4,202,332. A third configuration which achieves this same effect is a hybrid of the first two configurations wherein the annular withdrawal lumen is blocked at the distal end as described in U.S. Pat. Nos. 4,270,535 and 4,493,696.
Dual lumen catheters described in the prior art typically have three segments: a dual lumen tube, a coupling or transition device, and two single lumen tubes. The coupling provides an interface between the dual lumen tube and the single lumen tubes such that the fluids within each single lumen tube remain separated within the dual lumen catheter. A common coupling device is a "Y-shaped" juncture such as that described in U.S. Pat. No. 4,682,978. A problem with presently available dual lumen catheters is that the dual lumen tube runs in essentially a straight line in alignment with the site at which the catheter first enters a patient's body (the introduction site). This linear configuration leads to a substantial risk of infection at the introduction site. Unfortunately, the infection cannot be avoided by simply bending the dual lumen catheter without compromising the internal structure of the dual lumen tube.
The dual lumen catheters of the prior art also possess percutaneous access devices proximally located along the dual lumen tube to anchor the catheter within the patient during hemodialysis treatment. The coupling device, however, is externally located with respect to the patient's body. A drawback of presently available dual lumen catheters is that the external location of the coupling increases the risk of contamination within the dual lumen tube.
Another drawback of presently available dual lumen catheters is that they cannot remain within a patient for periods of one year or more. This is because the skin adjacent to the percutaneous access device of the implanted catheter does not heal to form a tight barrier to infection. Instead, when a dual lumen catheter is implanted, epidermal cells begin to migrate, each seeking to surround itself completely with other similar cells. Thus the epidermal cells grow alongside of the percutaneous access device in search of sister cells. Deep sinus tracts form and body fluids are exuded at the interface between the percutaneous access device and adjacent tissue thereby forming a bed for infection. If it is not expelled spontaneously, the implanted catheter must be surgically removed to allow the infection to be cured.
It is clear that a more effective device is needed to simultaneously infuse and withdraw fluids from a patient's body. Existing dual lumen catheters possess infusion ports in the catheter tip for advancing the catheter in a patient's body over a guide wire. The location of the infusion port for the axially located lumen causes stasis at the catheter tip and can disrupt the structural integrity of cells lining the body cavity. These catheters are not suitable for long-term applications. Thus, a multi-lumen catheter that minimizes stasis, reduces the risk of infection, and permits long-term skin penetration is desired.